Unitary air cleaner and flame arrester



June 25, 963 H. E. MGCRAY ETAL 3,094,978

UNITARY AIR CLEANER AND FLAME ARRESTER Filed Sept. 15. 1960 2 Sheets-Sheet 1 FIG. I

INVENTORE 7% 4 6i. 7/ 41 2 June 25, 1963 H. E. M CRAY ETAL 3,094,978

UNITARY AIR CLEANER AND FLAME ARRESTER Filed Sept. 15, 1960 2 Sheets-Sheet 2 l9 l9 v 25 [-1 I Ifi 1\ H gf fu nfiiiflkin 24 3; wbwgr swgmm FIG. 2

INVENTORS United StateS Patent UNITARY AIR CLEANER AND FLAME ARRESTER Harold Earl McCray and Loyd Bennie Paden, Pampa,

Tex., assignors to Cabot Corporation, Boston, Mass., a

corporation of Delaware Filed Sept. 15, 1960, Ser. No. 56,314 1 Claim. (Cl. 126-85) This invention comprises a unitary air cleaner and flame arrester for use in connection with heaters or furnaces employed in the oil and gas industry, particularly on pipe lines and meter houses where the heater must operate reliably without attention between long periods of inspection and without danger of either fire or of being blown out.

The device of our invention meets these exactly demands and successfully performs certain additional functions. In the first place, it controls and cleanses the air required for combustion. By reason of its construction, no direct blast of air is permitted to reach the burner. The path of the inlet air is made circuitous, and the air is divided in volume in reaching a tranquilizing zone from which it then passes, uniformly distributed, to the cleaning elements of the device. Under these conditions the cleaning elements operate with maximum efliciency. Dust, pollen and all other contaminants are removed from the admitted air which then flows peacefully on to the burner Without turbulence.

In the second place, the device of our invention is organized to include one or more flame arresting elements in the shape of wire mesh screens spaced from and lying below the cleaning elements. There is always the possibility that leakage of petroleum and its more volatile fractions, or of natural gas, may form an i-gnitable or explosive mixture that will be touched 01f by a flash back from the burner. In the device of my invention, the danger of flash back is obviated without obstructing or restricting the non-turbulent flow of cleaned air to the burner.

The desired objectives are secured in accordance with the present invention in a unitary device comprising an upright casing having a side outlet to the furnace and an open top inlet protected by an efiective rain shield. Within the upper end of the casing, and above the side outlet, air-cleaning pads and wire mesh flame arresters are sealed to the inner walls of the casing. Air flow passages are provided for dividing and distributing the incoming air so that it reaches the internal components of the casings in a uniform non-turbulent manner.

These and other features of the invention will be best understood and appreciated from the following description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawings in which:

FIG. 1 is a view of the unit in longitudinal section, and

FIG. 2 is a similar sectional view taken at right angles to that of FIG. 1.

The unitary air cleaner and flame arrester herein shown is constructed and arranged to be attached to any oil or gas burning furnace of commercial construction as indicated by reference character in FIG. 1 and shown as fired 'by a gas burner 11. The unit comprises an upright casing 12 of sheet metal herein shown, but not necessarily, as being substantially square in cross section and as having a circular outlet opening 13 in one of its .r 3,094,978 1C Patented June 25, 1963 side walls. The outlet opening is surrounded by an external throat or collar that is bolted to the furnace 10.

The bottom 14 of the casing is provided with a drain plug 15 and a stuffing box for the fuel gas pipe which serves the burner. The side wall opposite the outlet opening 13 is provided with a threaded fitting for a large plug 16 that may be removed for purposes of fighting the burner, inspection or otherwise.

A square extension sleeve 17 of sheet metal is fitted within the casing 12 and extends upwardly above its upper or inlet end forming an unobstructed air tranquilizing chamber or zone. Two opposite top edges of the sleeve 17 are upwardly convex and each is provided with a row of spaced air apertures 18 of approximately semi-circular shape as shown in FIG. 1. The other two top edges are flat or straight and provided with spaced semi-circular air apertures 19 all opening traversely into the air tranquilizing chamber.

The air cleaning components of the unit comprise a pair of spaced pads 20 having a frame which is sealed to the inner surface of the casing 12 or the extension sleeve 17 and a filling of aluminum foil or ribbons. The number and spacing of these pads is of secondary importance and may be varied in accordance with local conditions encountered in practice.

The flame-arresting components of the unit as herein shown comprise a pair of wire mesh screens 22 sealed in the casing below the pads 20 between a spacer 21 and a peripheral shoulder 21 that may be welded to the inner walls of the casing 12. Here again, the number and spacing of the wire mesh screens is of only secondary importance, but their employment in cooperation with the pads 20 is an important and novel feature of the invention.

Surmounting the casing 12 is a dome-shaped rain shield or cover 23 which is pitched in opposite directions as seen in FIG. 1 to fit the convex edges of the sleeve 17. The cover 23 has downwardly extending edge flanges or walls 24 that are spaced from the outer walls of the casing 12 so as to provide a peripheral air passage extending about all four sides of the casing and leading to the air apertures 18 and 19 in the upper edges of the sleeve 17. The cover is detachably held in place by a pair of bolts 25 welded at their lower ends to the outer walls of the casing. By turning down the nuts of these bolts, the pads 20 and screens 22 may be clamped in place against the underlying shoulder 21'.

In operation, the air required for combustion is drawn upwardly through the peripheral air passage, and inwardly through the apertures 18 and 19, whence it spreads into the tranquilizing zone formed by the sleeve 17 between the cover 23 and the uppermost pad 20. It then passes downwardly through the cleaning pads 20 and the wire mesh screens 22, arriving in non-turbulent flow at the combustion zone of the furnace.

Having thus disclosed our invention and described in detail an illustrative embodiment thereof, we claim as new and desire to secure by letters Patent:

A unitary air cleaner and flame arrester for use with heaters employed in the oil and gas industry, comprising an upright casing of rectangular cross section having an outlet adapted to lead to the heater in one side wall and an open top inlet, a rectangular sleeve having walls extending from within the casing upwardly above its open top, forming an open unobstructed tranquilizing chamber and having a series of" spacedair inlet apertures in its walls above said casing, a rectangular air-cleaning pad extending across the casing and serving as the bottom of the tranquilizing chamber, a wire mesh flame arrester of substantially the same area as the air-cleaning pad disposed in parallel relation thereto and sealed at its edges Within the casing, and a dome surrounding the upper portion of the sleeve, with clearance thus providing an upwardly extending peripheral air passage leading to the air inlet apertures in said sleeve.

UNITED STATES PATENTS Lukaszewski Jan. 27, 1920 Janosky "Feb. 1, 1944 Hagar Feb. 15, 1944 Glanzer July 10, 1956 Shepherd Oct. 31, 1961 FOREIGN PATENTS Canada July 22, 1958 France Feb. 19, 1940 

